I'm not sure how reliable information provided by a "source" can be, but the Globe and Mail has published an article stating that - according to a "source" - Jessica Lloyd was strangled, as well as Corporal Comeau. The "source" claims that Comeau was blind-folded and gagged before being asphyxiated, even though the theory is that she was meant to live.
Williams allegedly started stealing women's underwear back in 2006, and there are 48 cases in which stolen lingerie has been recovered. One of the creepier aspects (although not surprising, considering we know that people like Williams like to keep trophies) of the lingerie thefts is that all of it was found "neatly stored, catalogued and concealed".
Below is the link to the article. Please keep in mind that all of the information appears to be from a "source" and has yet to be confirmed by LE.
http://www.theglobeandmail.com/news/national/ontario-women-were-asphyxiated-source-says/article1465532/
ETA: The "source" claims that Comeau was asphyxiated, but doesn't use the word strangled.